- Synthesis of 3,4-dihydroisoquinolines using nitroalkanes in polyphosphoric acid
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A new method for the synthesis of 6,7-dimethoxy-3,4-dihydroisoquinoline based on the reaction of 2-(3,4-dimethoxyphenyl)ethan-1-amine (homoveratrylamine) with aliphatic nitro compounds in polyphosphoric acid (PPA) was developed.
- Aksenov,Malyuga,Abakarov,Aksenov,Voskressensky,Aksenov
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- Highly selective partial dehydrogenation of tetrahydroisoquinolines using modified Pd/C
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A highly selective procedure has been developed for the partial dehydrogenation of 1-substituted-1,2,3,4-tetrahydroisoquinolines over K3PO4·3H2O-modified Pd/C catalyst. This new method provides facile, atom-economical and environmentally friendly access to 1-substituted-3,4-dihydroisoquinolines without the need for stoichiometric amounts of harmful oxidants. The use of standard Pd/C as a catalyst for this process gave poor chemoselectivity. Pleasingly, the use of a K3PO4·3H2O-modified Pd/C catalyst promoted the partial dehydrogenation of 1-substituted-1,2,3,4-tetrahydroisoquinolines with excellent chemoselectivity by suppressing further dehydroaromatization. Furthermore, conducting the reaction under an atmosphere of oxygen led to further improvements in the chemoselectivity of the dehydrogenation, with the ratio of imine to isoquinoline reaching up to 32/1. The heterogenous Pd/C catalyst could also be recycled and reused at least three times with excellent conversion and chemoselectivity, demonstrating the significantly practical potential of this methodology.
- Ji, Yue,Chen, Mu-Wang,Shi, Lei,Zhou, Yong-Gui
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- A Visible-Light Promoted Amine Oxidation Catalyzed by a Cp*Ir Complex
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Through a rapid screening of Cp*Ir complexes based on a turn-on type fluorescence readout, a [Cp*Ir(dipyrido[3,2-a : 2’,3’-c]phenazine)Cl]+ complex was found to catalyze the blue-light promoted dehydrogenation of N-heterocycles under physiological conditions. In the dehydrogenation of tetrahydroisoquinolines, the catalyst preferentially yielded the monodehydrogenated product, accompanying H2O2 generation. We surmise that this mechanism may be reminiscent of flavin-dependent oxidases.
- Davis, Holly Jane,H?ussinger, Daniel,Ward, Thomas R.,Okamoto, Yasunori
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- Ionic liquids-assisted synthesis of 3,4-dihydroisoquinolines by the Bishler-Napieralski reaction
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The Bishler-Napieralski cyclodehydration of N-acyl-2-arylethylamines into the corresponding 3,4-dihydroisoquinolines with POCl3 as a dehydration reagent proceeds in ionic liquids under milder conditions and in higher yields.
- Epishina, Margarita A.,Kulikov, Alexander S.,Struchkova, Marina I.,Ignat'Ev, Nikolai V.,Schulte, Michael,Makhova, Nina N.
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- Enhancement of the carbamate activation rate enabled syntheses of tetracyclic benzolactams: 8-oxoberbines and their 5- And 7-membered C-ring homologues
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A route to the direct amidation of aromatic-ring-tetheredN-carbamoyl tetrahydroisoquinoline substrates was developed. This route enabled general access to 8-oxoberberines and their 5- and 7- membered C-ring homologues. It overcomes the undesired tandem side-reactions that result in the destruction of the isoquinoline backbone, which inevitably occurred under our previously reported superacidic carbamate activation method.
- Kurouchi, Hiroaki
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supporting information
p. 653 - 658
(2021/02/06)
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- Asymmetric Transfer Hydrogenation of Unhindered and Non-Electron-Rich 1-Aryl Dihydroisoquinolines with High Enantioselectivity
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The use of arene/Ru/TsDPEN catalysts bearing a heterocyclic group on the TsDPEN in the asymmetric transfer hydrogenation (ATH) of dihydroisoquinolines (DHIQs) containing meta- or para-substituted aromatic groups at the 1-position results in the formation of products of high enantiomeric excess. Previously, only 1-(ortho-substituted)aryl DHIQs, or with an electron-rich fused ring gave products with high enantioselectivity; therefore, this approach solves a long-standing challenge for imine ATH.
- Barrios-Rivera, Jonathan,Xu, Yingjian,Wills, Martin
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supporting information
p. 6283 - 6287
(2020/09/02)
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- Mechanistic Studies on Bioinspired Aerobic C-H Oxidation of Amines with an ortho-Quinone Catalyst
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We report herein our mechanistic studies of the ortho-quinone-catalyzed aerobic oxidation of primary, secondary, and tertiary amines. Two different catalytic pathways were discovered for the reductive half reactions: for primary amines, the reaction was found to proceed via a transamination pathway, while the reactions with secondary amines and tertiary amines proceeded via hydride transfer. We also found that the amine substrates could significantly promote the regeneration of the ortho-quinone catalyst in the oxidative half reaction, in which a proton transfer occurs between the amine substrates and catechol derivatives (the reduced form of the ortho-quinone catalyst).
- Zhang, Ruipu,Qin, Yan,Zhang, Long,Luo, Sanzhong
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supporting information
p. 2542 - 2555
(2019/03/08)
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- Josiphos-Type Binaphane Ligands for Iridium-Catalyzed Enantioselective Hydrogenation of 1-Aryl-Substituted Dihydroisoquinolines
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Convenient synthesis and useful application of a series of Josiphos-type binaphane ligands were described. The iridium complexes of these chiral diphosphines displayed excellent enantioselectivity and good reactivity in the asymmetric hydrogenation of challenging 1-aryl-substituted dihydroisoquinoline substrates (full conversions, up to >99% ee, 4000 TON). The use of 40% HBr (aqueous solution) as an additive dramatically improved the asymmetric induction of these catalysts. This transformation provided a highly efficient and enantioselective access to chiral 1-aryl-substituted tetrahydroisoquinolines, which were of great importance and common in natural products and biologically active molecules.
- Nie, Huifang,Zhu, Yupu,Hu, Xiaomu,Wei, Zhao,Yao, Lin,Zhou, Gang,Wang, Pingan,Jiang, Ru,Zhang, Shengyong
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supporting information
p. 8641 - 8645
(2019/10/17)
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- A Method for Bischler-Napieralski-Type Synthesis of 3,4-Dihydroisoquinolines
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A new method for the Bischler-Napieralski-type synthesis of 3,4-dihydroisoquinolines was developed by a Tf2O-promoted tandem annulation from phenylethanols and nitriles. Its success was mainly due to the fact that a phenonium ion was formed in the process and practically functioned as a stable and reactive primary phenylethyl carbocation.
- Min, Lin,Yang, Weiguang,Weng, Yunxiang,Zheng, Weiping,Wang, Xinyan,Hu, Yuefei
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supporting information
p. 2574 - 2577
(2019/04/30)
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- Synthesis and dopaminergic activity of a series of new 1-aryl tetrahydroisoquinolines and 2-substituted 1-aryl-3-tetrahydrobenzazepines
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A series of new 1-aryl-6,7-dihydroxy tetrahydroisoquinolines with several substitution patterns in the 1-aryl group at C-1 were prepared in good yields. The influence of each substituent on the affinity and selectivity for D1 and D2
- Lucena-Serrano, Cristina,Lucena-Serrano, Ana,Rivera, Alicia,López-Romero, Juan Manuel,Valpuesta, María,Díaz, Amelia
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supporting information
p. 480 - 491
(2018/07/13)
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- Electrochemical Acceptorless Dehydrogenation of N-Heterocycles Utilizing TEMPO as Organo-Electrocatalyst
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Catalytic acceptorless dehydrogenation (CAD) has been a basically important organic transformation to ubiquitous unsaturated compounds without the usage of a sacrificial hydrogen acceptor. In this work, we successfully developed the first electrochemical acceptorless dehydrogenation (ECAD) of N-heterocycles using TEMPO as the organo-electrocatalyst. We have achieved the catalytic dehydrogenation of N-heterocycles in an anode and the release of H2 in a cathode using an undivided-cell system. A variety of six-membered and five-membered nitrogen-heteroarenes can be synthesized in good yields in this system. In addition, this protocol can also be used in the application of important molecular synthesis. Our electrochemical strategy provides a mild and metal-free route for (hetero)aromatic compounds synthesis via the CAD strategy.
- Wu, Yong,Yi, Hong,Lei, Aiwen
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p. 1192 - 1196
(2018/02/14)
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- Method for solvent accelerated selective dehydrogenation of tetrahydroisoquinoline type compound
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The invention discloses a method for synthesizing 1-substituted-3,4-dihydroisoquinoline through the solvent accelerated selective partial dehydrogenation of a 1-substituted-1,2,3,4-tetrahydroisoquinoline compound. For a simple and easily obtained cyclic amine type compound such as a tetrahydroisoquinoline compound, a corresponding imine compound can be obtained through selective dehydrogenation; the conversion ratio of the cyclic amine type compound is higher; further, the proportion of a partially dehydrogenated product to a fully dehydrogenated product is more than 20 to 1. The method is simple and convenient to operate, is practical, easy and feasible, and is mild in reaction condition; the actual cost is greatly reduced. In addition, a method for synthesizing 3,4-dihydroisoquinoline through the direct dehydrogenation of tetrahydroisoquinoline has the advantages of atom economy and environmental friendliness.
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Paragraph 0039; 0040; 0041; 0042; 0043
(2017/07/22)
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- Cerium Chloride Catalyzed, 2-Iodoxybenzoic Acid Mediated Oxidative Dehydrogenation of Multiple Heterocycles at Room Temperature
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Catalytic cerium chloride was found to activate 2-iodoxybenzoic acid (IBX) for the oxidative dehydrogenation of tetrahydroisoquinolines, tetrahydro-β-carbolines, and thiazolidines to their dehydrogenated and aromatic forms at room temperature in moderate to excellent yields. The robustness of the protocol was demonstrated by scaling up the reactions to multigram quantities.
- Hati, Santanu,Sen, Subhabrata
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supporting information
p. 1277 - 1280
(2017/03/17)
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- Reactions of 3,4-dihydroisoquinolines and dihydrothieno[3,2-c]pyridines with benzyne
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Cyanomethyl-substituted tetrahydroisoquinolines and tetrahydrothieno[3,2-c]pyridines were synthesized by multicomponent reaction of the dihydro analogues of aforesaid systems with benzyne and acetonitrile. The products obtained relate to alkaloids of isoq
- Guranova, Natalia I.,Varlamov, Alexey V.,Ilyushenkova, Valentina V.,Sokolova, Ekaterina A.,Borisova, Tatiana N.,Aksenov, Alexander V.,Khrustalev, Viktor N.,Voskressensky, Leonid G.
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p. 506 - 508
(2017/10/05)
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- Palladium carbon catalyzed selective partial dehydrogenation method of tetrahydroisoquinoline
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The invention relates to a method for synthesis of 1-substituted-3, 4-dihydroisoquinoline by palladium carbon catalyzed selective partial dehydrogenation of a 1-substituted-1, 2, 3, 4-tetrahydroisoquinoline compound. The reaction temperature is 0-80DEG C. For easily available cyclic amine compounds like tetrahydroisoquinoline, a corresponding imine compound can be obtained through selective dehydrogenation, the conversion rate is up to 99%, and the proportion of a partial dehydrogenation product and a complete dehydrogenation product is greater than 20:1. The method provided by the invention has simple and practical operation, the raw materials and catalyst are cheap and easily available, the reaction conditions are mild, and the catalyst can be recycled, thus greatly reducing the actual cost. In addition, the method for synthesis of 3, 4-dihydroisoquinoline through direct dehydrogenation of tetrahydroisoquinoline has the advantages of atom economy and environmental friendliness.
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Paragraph 0044-0047; 0050
(2017/02/09)
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- O-Naphthoquinone-Catalyzed Aerobic Oxidation of Amines to (Ket)imines: A Modular Catalyst Approach
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A modular aerobic oxidation of amines to imines has been achieved using an ortho-naphthoquinone (o-NQ) catalyst. The cooperative catalyst system of o-NQ and Cu(OAc)2 enabled the formation of homocoupled imines from benzylamines, while the presence of TFA helped the formation of cross-coupled imines in excellent yields. The current mild aerobic oxidation protocol could also be applied to the oxidation of secondary amines to imines or ketimines with the help of cocatalyst, Ag2CO3, with excellent yields.
- Goriya, Yogesh,Kim, Hun Young,Oh, Kyungsoo
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supporting information
p. 5174 - 5177
(2016/10/14)
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- Solvent-promoted highly selective dehydrogenation of tetrahydroisoquinolines without catalyst and hydrogen acceptor
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An unusual solvent DMF-promoted dehydrogenation of 1-substituted 1,2,3,4-tetrahydroisoquinolines to synthesize cyclic imines is described. This environmentally friendly reaction features no requirement of any metal catalysts, oxidants, or hydrogen acceptors. A wide range of structurally varied 3,4-dihydroisoquinolines can be obtained with good yields and excellent chemoselectivities.
- Feng, Guang-Shou,Ji, Yue,Liu, Hui-Fang,Shi, Lei,Zhou, Yong-Gui
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supporting information
p. 747 - 749
(2016/02/05)
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- Bioinspired organocatalytic aerobic C-H oxidation of amines with an ortho -quinone catalyst
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A simple bioinspired ortho-quinone catalyst for the aerobic oxidative dehydrogenation of amines to imines is reported. Without any metal cocatalysts, the identified optimal ortho-quinone catalyst enables the oxidations of α-branched primary amines and cyclic secondary amines. Mechanistic studies have disclosed the origins of different performances of ortho-quinone vs para-quinone in biomimetic amine oxidations.
- Qin, Yan,Zhang, Long,Lv, Jian,Luo, Sanzhong,Cheng, Jin-Pei
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supporting information
p. 1469 - 1472
(2015/03/30)
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- Enantioselective Synthesis of 1-Aryl-Substituted Tetrahydroisoquinolines Through Ru-Catalyzed Asymmetric Transfer Hydrogenation
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A convenient and general asymmetric transfer hydrogenation of a wide array of 1-aryl-3,4-dihydroisoquinoline derivatives using a [RuIICl(η6-benzene)TsDPEN] complex in combination with a 5:2 HCOOH-Et3N azeotropic mixture as a hydrogen source was developed. Under mild reaction conditions, the described catalytic transformation secured a practical synthetic access to the corresponding valuable chiral 1-aryltetrahydroisoquinoline units with high atom economy, a broad substrate scope, high isolated yields (up to 97%) and good to excellent enantioselectivities (up to 99% ee). It was found that the stereochemical outcome of the reaction was strongly influenced by both the structure of the catalyst and the substituents present on the substrate. The synthetic utility of the present protocol has been demonstrated through the asymmetric synthesis of several biologically important alkaloids including the antiepileptic drug agent 1c, as well as (-)-nor-cryptostyline alkaloids I and II.
- Perez, Marc,Wu, Zi,Scalone, Michelangelo,Ayad, Tahar,Ratovelomanana-Vidal, Virginie
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p. 6503 - 6514
(2015/10/19)
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- Bioinspired aerobic oxidation of secondary amines and nitrogen heterocycles with a bifunctional quinone catalyst
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Copper amine oxidases are a family of enzymes with quinone cofactors that oxidize primary amines to aldehydes. The native mechanism proceeds via an iminoquinone intermediate that promotes high selectivity for reactions with primary amines, thereby constraining the scope of potential biomimetic synthetic applications. Here we report a novel bioinspired quinone catalyst system consisting of 1,10-phenanthroline-5,6-dione/ZnI2 that bypasses these constraints via an abiological pathway involving a hemiaminal intermediate. Efficient aerobic dehydrogenation of non-native secondary amine substrates, including pharmaceutically relevant nitrogen heterocycles, is demonstrated. The ZnI2 cocatalyst activates the quinone toward amine oxidation and provides a source of iodide, which plays an important redox-mediator role to promote aerobic catalytic turnover. These findings provide a valuable foundation for broader development of aerobic oxidation reactions employing quinone-based catalysts.
- Wendlandt, Alison E.,Stahl, Shannon S.
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supporting information
p. 506 - 512
(2014/01/23)
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- Mild and efficient syntheses of 1-aryl-3,4-dihydroisoquinolines and 1-aryl-3,4-dihydro-β-carbolines via regiospecific β-eliminations of the corresponding N-tosyl-1,2,3,4-tetrahydroisoquinolines and N-tosyl-1,2,3,4-tetrahydro-β-carbolines
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(Chemical Equation Presented) Treatment of N-tosyl-1-aryl-1,2,3,4- tetrahydro-isoquinolines or N-tosyl-1-aryl-1, 2,3,4-tetrahydro-β-carbolines with a strong base such as NaOH or KOH at 70 °C in dimethylsulfoxide (DMSO) produced 1-aryl-3,4-dihydroisoquinolines or 1-aryl-3,4-dihydro-β- carbolines in good yields via mild and regiospecific β-eliminations. A dramatic solvent effect was observed, DMSO was crucial for the reactions. The temperature is also crucial for the reactions and should be kept between 60 and 80 °C. Copyright Taylor & Francis Group, LLC.
- Dong, Jing,Shi, Xiao-Xin,Xing, Jing,Yan, Jing-Jing
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experimental part
p. 2806 - 2817
(2012/07/16)
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- Palladium-catalyzed intramolecular C-H amidation: Synthesis and biological activities of indolobenzazocin-8-ones
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The synthesis of multi ring-fused indolobenzazocinone derivatives, an antimitotic agent, has been carried out using palladium-catalyzed C-H activation/intramolecular amidation of benzo[d]azocinones, which were synthesized by the ring annulations of dihydroisoquinolines and azlactone in refluxing acetonitrile. The target compounds, indolobenzazocin-8-one derivatives, were evaluated for their cytotoxicity against the cancer cell lines HUCCA-1, A549, HepG2, and MOLT-3. The results showed that an unsubstituted indolobenzazocin-8-one 1e exhibited very good activities in the nanomolar IC50 value range (HepG2 and MOLT-3).
- Boonya-Udtayan, Sasiwadee,Ruchirawat, Somsak,Mahidol, Chulabhorn,Thasana, Nopporn,Eno, Meredith
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p. 10293 - 10301,9
(2012/12/12)
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- Palladium-catalyzed intramolecular C-H amidation: Synthesis and biological activities of indolobenzazocin-8-ones
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The synthesis of multi ring-fused indolobenzazocinone derivatives, an antimitotic agent, has been carried out using palladium-catalyzed C-H activation/intramolecular amidation of benzo[d]azocinones, which were synthesized by the ring annulations of dihydroisoquinolines and azlactone in refluxing acetonitrile. The target compounds, indolobenzazocin-8-one derivatives, were evaluated for their cytotoxicity against the cancer cell lines HUCCA-1, A549, HepG2, and MOLT-3. The results showed that an unsubstituted indolobenzazocin-8-one 1e exhibited very good activities in the nanomolar IC50 value range (HepG2 and MOLT-3).
- Boonya-Udtayan, Sasiwadee,Eno, Meredith,Ruchirawat, Somsak,Mahidol, Chulabhorn,Thasana, Nopporn
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p. 10293 - 10301
(2013/01/15)
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- A highly efficient and enantioselective access to tetrahydroisoquinoline alkaloids: Asymmetric hydrogenation with an iridium catalyst
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Efficient and enantioselective: Using the iodine-bridged dimeric iridium complex [{Ir(H)[(S,S)-(f)-binaphane]}2(μ-I)3] +I- (1) a wide range of tetrahydroisoquinoline alkaloids, including the substructure of the pharmaceutical drug solifenacin, were obtained with excellent enantioselectivities and high turnover numbers (see scheme). Copyright
- Chang, Mingxin,Li, Wei,Zhang, Xumu
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supporting information; experimental part
p. 10679 - 10681
(2011/12/05)
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- Diastereoselective synthesis of 1,2-disubstituted 2,3,4,5-tetrahydro1H-3- benzazepines by means of the Stevens rearrangement
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1,2-Disubstituted 2,3,4,5-tetrahydro-1H-3-benzazepines were conveniently obtained by making use of the regio- and diastereoselective Stevens rearrangement of the corresponding isoquinolinium salts with 1,8-diazabicyclo[5.4.0]undec-7-ene in acetonitrile, T
- Valpuesta, Maria,Ariza, Manuela,Diaz, Amelia,Suau, Rafael
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experimental part
p. 4393 - 4401
(2010/10/04)
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- Strategies and synthetic methods directed toward the preparation of libraries of substituted isoquinolines
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Strategies for the production of substituted isoquinoline libraries were developed and explored. Routes involving microwave-assisted variants of the Bischler-Napieralski or Pictet-Spengler reaction allowed for cyclization of substituted β-arylethylamine derivatives. The dihydroisoquinolines and tetrahydroisoquinolines thus generated could then be oxidized to their corresponding isoquinoline analogues. An alternate strategy, however, involving the preparation and activation of isoquinolin-1(2H)-ones is demonstrated to be a more practical, rapid, and efficient route to C1- and C4-substituted isoquinoline libraries.
- Awuah, Emelia,Capretta, Alfredo
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experimental part
p. 5627 - 5634
(2010/11/03)
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- 1-Aryl-3,4-dihydroisoquinoline inhibitors of JNK3
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A series of 1-aryl-3,4-dihydroisoquinoline inhibitors of JNK3 are described. Compounds 20 and 24 are the most potent inhibitors (pIC50 7.3 and 6.9, respectively in a radiometric filter binding assay), with 10- and 1000-fold selectivity over JNK2 and JNK1,
- Christopher, John A.,Atkinson, Francis L.,Bax, Benjamin D.,Brown, Murray J.B.,Champigny, Aurelie C.,Chuang, Tsu Tshen,Jones, Emma J.,Mosley, Julie E.,Musgrave, James R.
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scheme or table
p. 2230 - 2234
(2009/12/25)
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- A highly enantioselective access to tetrahydroisoquinoline and β-carboline alkaloids with simple noyori-type catalysts in aqueous media
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Silver enhancement: A very convenient modified protocol for the enantioselective transfer hydrogenation of dihydroisoquinoline skeletons under aqueous conditions is reported. Unmodified Noyori ligands can be used and the activity of the catalyst is greatly enhanced with silver additives (see scheme). The protocol was used in a very short synthesis of the alkaloids (S)-harmicine and (S)-crispine.
- Evanno, Laurent,Ormala, Joel,Pihko, Petri M.
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supporting information; experimental part
p. 12963 - 12967
(2010/06/16)
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- A versatile cyclodehydration reaction for the synthesis of isoquinoline and β-carboline derivatives
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(Chemical Equation Presented) The direct conversion of various amides to isoquinoline and β-carboline derivatives via mild electrophilic amide activation, with trifluoromethanesulfonic anhydride in the presence of 2-chloropyridine, is described. Low-temperature amide activation followed by cyclodehydration upon warming provides the desired products with short overall reaction times. The successful use of nonactivated and halogenated phenethylene derived amides, N-vinyl amides, and optically active substrates is noteworthy.
- Movassaghi, Mohammad,Hill, Matthew D.
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supporting information; experimental part
p. 3485 - 3488
(2009/05/07)
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- A very mild access to 3,4-dihydroisoquinolines using triphenyl phosphite-bromine-mediated bischler-napieralski-type cyclization
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Substituted β-phenylethylamides undergo smooth intramolecular cyclization to 3,4-dihydroisoquinolines in good to excellent yields when treated with bromotriphenoxyphosphonium bromide at -60°C in dichloromethane in the presence of triethylamine. The reaction proceeds under the mildest conditions ever reported for Bischler-Napieralski-type cyclizations. When chlorotriphenoxyphosphonium choride is used, low yields are obtained instead. Georg Thieme Verlag Stuttgart.
- Vaccari, Daniele,Davoli, Paolo,Ori, Claudia,Spaggiari, Alberto,Prati, Fabio
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experimental part
p. 2807 - 2810
(2009/05/07)
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- Photocyclization of 1-(2-halophenyl)-3,4-dihydro-6,7- dimethoxyisoquinolines: A short and new synthesis of triclisine
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A short and new synthesis of the non-phenolic azafluoranthene alkaloid triclisine utilizing the photocyclization of 1-(2-halophenyl)-3,4-dihydro-6,7- dimethoxyisoquinolines as a key step has been described.
- Ramana,Sharma,Parihar
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p. 4385 - 4386
(2007/10/03)
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- Synthesis of 3,4-dihydroisoquinolines, 2-alkyl(acyl)-1(2H)-3,4-dihydroisoquinolinones, 2-alkyl-1(2H)-isoquinolinones and 1-alkyl-2(2H)-quinolinones by oxidation with potassium permanganate
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Synthesis of 3,4-dihydroisoquinolines 2, 2-alkyl- 6 and 2-acyl-3,4-dihydro-1(2H)-isoquinolinones 9, 2-alkyl-1(2H)-isoquinolinones 14, N-alkyl-3,4-dihydro-2(2H)-quinolinones 16 and N-alkyl-2(2H)-quinolinones 19 by oxidation of 1,2,3,4-tetrahydroisoquinolines 1, N-alkyl (acyl)iminium salts of 3,4-dihydroisoquinolines 5,8 and isoquinoline 13 as well as of N-alkyl ammonium salts of tetrahydroquinoline 15 and quinoline 18 with potassium permanganate is described.
- Venkov,Statkova-Abeghe
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p. 1451 - 1460
(2007/10/03)
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- Synthesis of isoquinolines from 2-phenylethylamines, amides, nitriles and carboxylic acids in polyphosphoric acid
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A convenient one pot synthesis of 1-, 1.3-substituted 3,4-dihydroisoquinolines 5 enamines 10 and 3-oxo-2,3-dihydroisoquinolines 18 as well as of enamides 22 of isoquinoline from 2-phenyl-, 1,2-diphenylethylamines, phenylacetamides, phenylacetonitriles, N-acylphenylethylamines and carboxylic acids in nonaqueous media has been accomplished.
- Venkov, Atanas P.,Ivanov, Ilian I.
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p. 12299 - 12308
(2007/10/03)
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- Synthesis and Molecular Modeling of 1-Phenyl-1,2,3,4-tetrahydroisoquinolines and Related 5,6,8,9-Tetrahydro-13bH-dibenzoquinolizines as D1 Dopamine Antagonists
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New 1-phenyl-1,2,3,4-tetrahydroisoquinolines and related 5,6,8,9-tetrahydro-13bH-dibenzo-quinolizines were prepared as ring-contracted analogs of the prototypical 1-phenyl-2,3,4,5-tetrahydrobenzazepines (e.g., SCH23390) as a continuation of our studi
- Minor, Deborah L.,Wyrick, Steven D.,Charifson, Paul S.,Watts, Val J.,Nichols, David E.,Mailman, Richard B.
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p. 4317 - 4328
(2007/10/02)
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- Synthesis and spectral properties of 6,7-dimethoxy-1-[(ortho; and para-R)-phenyl]-3,4-dihydroisoquinoline
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The preparation of eleven novel 6,7-dimethoxy-1-[(ortho, and para-R)-phenyl]-3,4-dihydroisoquinolines with possible pharmacological activity is described. The structure of all products was corroborated by ir, 1H nmr, 13C-nmr, and ms.
- Cortes Cortes,Cortes Romero,Gutierrez Ramirez
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p. 1425 - 1427
(2007/10/02)
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- STUDIES ON FRIEDEL-CRAFTS ACYLATION OF N-ACETYLHOMOVERATRYLAMINE AND PREPARATION OF 1-SUBSTITUTED 3,4-DIHYDRO-6,7-DIMETHOXYISOQUINOLINES
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Friedel-Crafts acylation of N-acetylhomoveratrylamine in a molar ratio of 1:2:3 of 1, AlCl3 and the appropriate acid chloride using nitrobenzene as solvent gave the corresponding 2-acyl derivatives 2a-j in good yields.Subsequent treatment of 2 in boiling
- Orito, Kazuhiko,Matsuzaki, Tsutomu,Suginome, Hiroshi,Rodrigo, Russel
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p. 2403 - 2412
(2007/10/02)
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- AZAFLUORANTHENE ALKALOIDS: A REINVESTIGATION OF THE SYNTHESIS OF 5,6-DIMETHOXYINDENOISOQUINOLINE
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The title alkaloid has been synthesized via thermolysis of an isolated triazinium salt.The resulting dihydro alkaloid is described for the first time.The reported synthesis of the alkaloid was reinvestigated, with isolation of two products not previously obtained during its preparation.
- Menachery, Mary D.,Buck, Keith T.
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p. 2677 - 2679
(2007/10/02)
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- NOVEL CONDENSING AGENTS FOR BISCHLER-NAPIERALSKI TYPE CYCLODEHYDRATION
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Trifluoroacetic anhydride and trifluoromethyl sulfonyl anhydride are used in Bischler-Napieralski type cyclization.Starting from the appropriate amides, the dihydroisoquinolines are formed in excellent yields.
- Nagubandi, Sreeramulu,Fodor, G.
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p. 165 - 177
(2007/10/02)
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- The mechanism of the Bischler-Napieralski Reaction
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The Bischler-Napieralski dihydroisoquinoline synthesis was proven to occur via imidoyl chlorides and the corresponding nitrilium salt.Two-step process required much milder conditions (20 degC - 50 degC) compared to drastic classical conditions of refluxing at 100 degC - 200 degC.The Bischler-Napieralski reaction is shown to share a common intermediate with two other well-known reactions: the von Braun and the Ritter reactions
- Nagubandi, Sreeramulu,Fodor, G.
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p. 1457 - 1463
(2007/10/02)
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